Bactericides/fungicides are known in the art as agents used to protect agricultural crops from damage caused by pathogenic bacteria/fungi. The use of such products is necessitated by the great losses caused by such organisms. To be economical, the cost of controlling plant diseases by the application of a bactericide/fungicide product must be offset by increased crop yield and quality.
Agricultural bactericides/fungicides are available in different types of formulations including wettable powders, emulsifiable concentrates, water-based flowables, and dry flowables (also known as water dispersible granules). Dry flowable products are generally dustless, free-flowing, granular products. Dry flowable formulations have recently gained in popularity among users because they offer advantages such as improved shelf life, substantially no dusting, easy pouring, a higher percentage of active ingredient, and more convenient packaging than other formulation types.
Copper based bactericides/fungicides are used extensively in agriculture. Several dry flowable copper based bactericides/fungicides are known in the art, these being: "Kocide DF" available from Griffin Corporation of Valdosta, Ga.; "Blueshield DF" and "Nu-Cop WDG" available from Micro Flo Company of Lakeland, Fla.; and "Sandoz COC DF" and "Sandoz Cu.sub.2 O DF" available from Sandoz Ltd. of Switzerland.
Cupric hydroxide by itself is unstable. However, it is known in the art that cupric hydroxide can be stabilized by a phosphate process. U.S. Pat. No. Re. 24,324 (the disclosure of which is incorporated herein by reference) relates to a method of making stable cupric hydroxide. U.S. Pat. No. 3,428,731 (the disclosure of which is also incorporated herein by reference) relates to dispersions of phosphate stabilized cupric hydroxide. That patent discloses that aqueous dispersions of finely divided phosphate-process cupric hydroxide can be prepared by carefully regulating the pH of the dispersion and the calcium hardness of the aqueous vehicle. The patent also discloses that approximately 1% to 3% by weight of a didpersant should be added to the aqueous vehicle before the phosphate-process cupric hydroxide is added. Suitable dispersing agents are disclosed as including sodium lignosulfonate, the sodium salt of a polymeric carboxylic acid, sulfonated naphthalene, technical protein colloid, tallow dimethyl benzyl ammonium chloride, the sodium salt of polymerized alkyl aryl sulfonic acid, diethanolamide of a special fraction of coconut fatty acids, the sodium salt of condensed mono-naphthalene sulfonic acid and isooctyl phenyl polyethoxy ethanol.
The prior art copper based bactericide/fungicide products require the use of relatively large amounts of copper to effectively control disease. This relatively high level of copper detracts from cost effectiveness, contributes to soil residue problems and raises the potential for phytotoxicity. In addition, the methods used to produce these prior art products are not always cost effective.
Therefore, a need exists for a dry flowable copper based bactericide/fungicide formulation and a cost effective method for producing a dry flowable copper based bactericide/fungicide formulation which provides increased biological activity compared to conventional dry products and with a lower copper use rate when applied to crops.